This weekend on Kamen Rider Build, we learn that Sento's father is alive and well and we will also get to know the truth behind the Best Matches.

Episode 41 "The truth behind the Baste Matches" 6/24/18

"Shinobu Katsuragi, Sento's father and the lead researcher behind the Pandora Box and Ryuga Banjou... is still alive?! In order to confirm if this was true, Ryuga was given an important piece of data. The data contains a recording made by Shinobu Katsuragi relaying information on the designs of the Build System.

Furthermore, there is also information within that contains the truth behind all the Best Matches! Why "Rabbit" and "Tank" are considered to be Best Matches? When Sento starts to uncover the truth behind them, Misora's expression suddenly starts to change..."